DoE Scientists Conclude Electric Cars Will “Meet The Daily Travel Needs Of Drivers Longer Than Commonly Assumed”

APR 26 2015 BY MARK KANE 46

2015 Nissan LEAF

2015 Nissan LEAF

On the statistics side, for years we heard that the range of electric cars like the Nissan LEAF (84 miles EPA) will meet driving needs for the majority of drivers.

Recently, a study led by Samveg Saxena, Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) researcher, went a step further by simulating battery capacity fade.

According to the study, the assumption that EV batteries will be retired after the battery has lost 20 percent is not necessarily is true – at least on the statistical level a drop of 20% of range in a Nissan LEAF still meets more than 85 percent of U.S. drivers’ needs.

Interesting is that even a 50% drop in theory should be above the needs of 80% of drivers (and a 70% drop would meet 55% of drivers’ need), but we all know that drivers aren’t robots and that most want to have some reserve of range. Tesla Motors on the other side is aiming at over 200 miles of real world range for new cars.

“To conduct the study, the researchers took nearly 160,000 actual driving itineraries from the National Household Travel Survey conducted by the Department of Transportation. These are 24-hour travel itineraries showing when a car was parked or driving, including both weekend and weekday usage by drivers across the United States.

The researchers then assumed all itineraries were driven using a vehicle with specifications similar to a Nissan Leaf, which has about 24 kilowatt-hours of energy storage capacity, similar to many other EVs on the market, and 400 kW of discharge power capability, which was based on battery cell-level measurement data for the chosen vehicle.”

Saxena, who has a PhD in mechanical engineering, said:

“There are two main reasons people are hesitant to buy an EV: first, they’re unsure it will satisfy their mobility needs, and second, they’re afraid the battery won’t last the whole life of the car and they’ll have to replace it for a lot of money. We show that, even after substantial battery degradation, the daily travel needs of most people are still going to be met.”

Impact of battery capacity fade on the ability of EVs to satisfy the normal weekend travel needs of U.S. drivers for several scenarios of charger availability (source: Berkeley Lab)

Impact of battery capacity fade on the ability of EVs to satisfy the normal weekend travel needs of U.S. drivers for several scenarios of charger availability (source: Berkeley Lab)

Interesting is the part of the study on charging scenarios. Even the smaller battery pack with significant capacity fade could be good enough if drivers are able to charge at work.

Cheap L1 charging stations at workplaces could extend useful life of EVs and expand the market for potential buyers that are concerned over range.

“People have commonly thought, ‘if I buy an EV, I’ll have to replace the battery in a few years because I’ll lose the ability to satisfy my driving needs, and it’s not worth it,’” Saxena said. “We have found that only a small fraction of drivers will no longer be able to meet their daily driving needs after having lost 20 percent of their battery’s energy storage capabilities. It is important to remember that the vast majority of people don’t drive more than 40 miles per day on most days, and so they have plenty of reserve available to accommodate their normal daily trips even if they lose substantial amounts of battery capacity due to degradation.”

As the battery continues to degrade down to 50 percent of its original energy storage capacity, the research found that the daily travel needs of more than 80 percent of U.S. drivers can still be met, and at 30 percent capacity, 55 percent of drivers still have their daily needs met. “Even if a driver has a long, unexpected trip beyond the normal daily travel, an EV battery with substantial capacity fade can often still make the trip,” Saxena said.”

The full article “Quantifying EV battery end-of-life through analysis of travel needs with vehicle powertrain models,” is available here.

Source: Berkeley Lab

Categories: General


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46 Comments on "DoE Scientists Conclude Electric Cars Will “Meet The Daily Travel Needs Of Drivers Longer Than Commonly Assumed”"

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Here is the thing about the average daily number that people thing you only need like 40 miles for. I work 20miles round trip to work. If after work I HAVE TO go out to my brothers, its just not going to work out for me, he lives 40 miles away… how is a car that can only go MAYBE one way (poor weather for example) help me at all? just make a damn car that goes 150 miles to start with and actually sell some cars!

Spot on.

It doesn’t take many times of, I can’t go because I don’t have enough charge, before you are willing to pay for a 150+ mile battery.

What is sad is the amount of programming from certain news media outlets that has caused this line of thinking, especially with the millions of aging hybrid batteries out there. For me, the most interesting data from the second graph is that no more than 8% separates an L1 @ home + L1 @ work compared to L1 everywhere, even with only 30% remaining battery life. I am sure the divide doubles with L2 everywhere, but it just seems irrelevant when the 200 mile BEVs start to arrive in 2017. Nothing is left to argue about then except long range travel. When you take a trip with 100% charge on the first leg and stop for an 80% charge on the second, exactly what is the percentage of trips remaining? I know some people work completely outside of those numbers and we should give them a pass to keep driving whatever it is they are driving. If they want to join the electric movement, I’ve got one word for them,.. EREV… My family’s desire to road trip is similar to that of contributors Assaf and Steve Coram. When we do so, we are on va-caaaa-tion!30 minutes – hour stops are… Read more »

I wonder if OEMs made more user friendly connections to mobile portable generators, it would knock out another percentage, or is the percentage just too small to make sense?

You’re talking about towing a “genset” trailer; that is, a trailer containing a generator powerful enough to keep the BEV charged as you travel?

Two problems:

(1) Towing a trailer is inconvenient, and towing it safely requires you to limit speed on a highway. Since this would only be done on long-distance trips where one generally would like to travel at full highway speed, the usefulness seems rather limited.

(2) Few if any people are going to buy and store a genset trailer. If you have to go to the trouble and expense of renting one every time you want to take a long-distance trip, then why not just rent a gas guzzler or PHEV for those trips? It would be a lot more convenient to drive a gas guzzler on a long distance trip, and as they say: Convenience is worth paying for.

* * * * *

It has been suggested that, for example, U-Haul might rent genset trailers for BEV drivers wanting to extend the range of their car. But for the above reasons, I doubt that’s ever going to be popular.

My current plan when I buy my used EV the Nissan leaf or i-miev is to run it as is for local trips. The 900 pound Gorilla in all of this is if I move or get a different job that raises my range needs by a huge deal. Then I will start looking for a bigger more energy dense battery. But in terms of having a EV with a dying battery by the time that happens batteries will have double or triple the power of the old so it will be more of a upgrade then a replacement.

I’ve given thought to the same concept, a late model Leaf at CarMax isn’t too pricey any more. HOWEVER, when battery change time comes, and it will come unless you trade or total the car first, will those better batteries be available to fit the used EV I purchased. I’ll be contemplating this a while longer whilst I finish paying off my current ride.

A Nissan guy- who wishes to stay anonymous, of course- told me yes.

I visited this one website were for a fee they will swap out your old Prius batteries and add lithium. On top of that they will add a plug to your Prius and give it a 40 to 50 mile plug in range.

Another very interesting point of the study is the small incremental value of L1 vs L2 charging at work. I lobbied my employer into installing L1 charging stations at work. That is a much easier sell than L2 chargers. L1 chargers are cheaper to set up and slower. The slower part turns out to be very beneficial for workplace charging. L1s are so slow that the amount of electricity used is small (and cheap for the employer) and no outside user is likely to ever hook up. So you don’t need fancy stations with user access, payment or web connectivity features, reducing cost even further.

My employer put in an L2 for the “exclusive use” of an experimental BEV service vehicle they were testing.

At the end of the test, the converted BEV “went away” and the spot where the charger is, had an ISO container sitting in it. Nothing says go away like a two-ton metal box.

I have a 2012 Nissan leaf. I live in Baltimore Maryland. Before I got the Leaf I used to take my wife and kids to chesapeake Beach (also known as North Shore Beach). I haven’t taken that trip since I got the Nissan Leaf. I would like a car that not only satisfy my weekly transportation needs, but also satisfy my weekend transportation wants (trips of pleasure). This is why my next car will be an extended range electric vehicle. With the Nissan leaf I have never gotten stuck on the road and ended up on the back of a flatbed tow truck, but I came awfully close several times.

Or buy a Chevy Bolt with a 200 mile range when they come out in late 2016. Or a Tesla Model 3 with a 200 mile range.

it sounds like you learned the hard way that it is not a good idea to buy an BEV as your only car…

i think these kinds of experiences are bad for EV adoption in general. you should have purchased a PHEV, like the chevrolet volt, even though the volt advertised less electric range.

I live in melbourne Australia so my opinion might not be all that valid for the American market in particular the sub-zero range issues but we are a family of 4 and we only have a leaf and everything is great, no problem at all.

If u are thinking about a leaf pull up google maps and put in all the journeys u want to take and work it out. 6 months and nearly 10,000km and I’m not missing anything.

In theory, practice and theory are the same. In practice, they are not.


I think these researchers are being too theoretical. They need to drive EVs themselves.


I had a teacher who said something like that.

It doesn’t cease to amaze me how these engineers in white lab coats will come up with facts and figures and determine what the public’s transportation needs are.

The scientists in this paper used actual data from thousands of journeys, real journeys taken by real people. They developed a reasonably complex model based on real performance data that took into account a number of degradation processes to predict how a car with battery fade would perform.

They didn’t make anything up, they live in the real world, you appear to live on cloud 9. They can justify their conclusions in a peer reviewed journal article you make a false accusation don’t justify your conclusions and don’t provide an alternative conclusion.

They need to add cold & mostly freeway travel into the mix. Leaf range can drop to 60 miles.

And then add a reasonable buffer for WAF.

I am just wondering:

How many of you actually read the entire research before commenting here, especially those that keep saying, “oh, I can’t make that trip,” or “i need a vehicle that can drive further away;” and

Did you actually know the capability of the vehicle you bought (e.g. LEAF) before saying it’s not providing enough range, or did you actually KNOW what you bought, only to have wanted it to do something you wanted it to do, outside of its capability. then complained? It’s like, “oh, the lamborghini I have is not giving me enough trunk space and ground clearance for my hauling trips…”

I don’t think we should blame car buyers for not having a fully detailed understanding of the electric range of whatever BEV or PHEV they’re considering buying. Nissan advertised the Leaf as a “100 mile EV”… and still does at car shows. Even the EPA range rating isn’t that useful, because it’s just an average for average conditions. To get even a basic understanding of a plug-in EV’s electric range, we need a chart, with one axis showing the average speed of the trip, and the other axis showing the outside temperature at the beginning of the trip. I have yet to see such a chart for -any- car, plug-in EV or otherwise. Auto manufacturers are not interested in showing the limitations of EV range under different conditions; they’re just interested in advertising that you can get “up to” a certain range, and deliberately don’t mention you’ll get that range only under ideal conditions. Even such a chart wouldn’t be adequate to cover such variables as whether or not the driver uses cabin heating/AC, traffic conditions such as traffic jams and detours, or weather conditions such as a strong headwind or tailwind. If you really want to get down into… Read more »

I take it that you didn’t read the research paper link…? If not, please do.

It’s the result of polling 216 THOUSANDS data point, and how today’s EV (range) – those that are affordable – should satisfy most of the population, even with battery degradation.

The report isn’t actually about the advertised driving range, or how speed affects range, etc.

May I suggest you read the paper more closely.

They took the data you talk about, but instead of using that to create an analysis, they created a simulation, or computer model, and then used the results they got from running that simulation for their analysis!

Heaven save us from Ivory Tower types.

Londo, the word “simulation” appears several times in the paper, so I’m puzzled that you missed it.

The rather glaring flaw in this article’s argument has already been discussed in several posts above. What might be barely sufficient for an -average- daily drive is absolutely -not- sufficient for the average driver, because the average driver drives further on some days than others. What this article is advocating is that people should get a car that has a range barely adequate for 50% of their trips. The article notes “we all know that drivers aren’t robots and that most want to have some reserve of range.” (And I think even a robot driver would be programmed to require a reserve, because range estimates are exactly that — just estimates.) But that’s only a part of the problem, and probably not even the most important part. People will start thinking seriously about using a BEV as their daily driver, and not just as a second car, when BEVs have a range sufficient for more than 90% of their trips. Not a mere 50%! Looking forward to those nominally “200 mile” EVs coming in 2017. Of course, the real-world range will likely be something like 150-160 miles, but still that should be sufficient to hit that more-than-90%-of-trips target, for most… Read more »

Whether or not to replace a battery on an existing EV is a decision taken by a driver with complete information about the capabilities of his or her car and the range required. Therefore the main result of the study, namely that the common assumption that batteries will be replaced at 80% capacity is likely flawed, is completely reasonable.

Absolutely that conclusion is reasonable, and in fact I’ve seen some posts saying the same. (Of course, anecdotal evidence isn’t conclusive.) But if you read the actual study, it repeatedly says -simulations- were used, for everything. Not data from actual EV drivers. As was already said in a comment above: In theory, there’s no difference between theory and practice. But in practice, there is. A rather glaring omission is any mention of variation in range due to temperature. For example, the bit about L1 chargers being sufficient for work charging is only true in regions with a mild climate. If it often gets below freezing, then even workplace charging will need L2 power. A car that’s plugged in will (or at least might) use the external power to run the battery heater, which in some conditions may cause charging to be too slow to restore much range at all. The state of the art of EV batteries is advancing so rapidly that I question anyone will be willing to pay full price for a replacement pack identical to the original pack. Any replacement needed within the first few years should be covered under warranty, and after that, I think PEV… Read more »

the reason why an L1 EVSE is sufficient for workplace recharging is based on the assumption that the car is parked all day, which i assume in turn makes the assumption that “all day” means at least 8 hours.

If leaving a plug-in EV on a L1 charger overnight, in very cold weather, can result in very little charging because most of the power is being used to run the battery heater, than leaving it on a L1 charger at work will have the same problem.

I don’t know how common that problem is, but this was reported as a real-world problem which makes a L1 charger inadequate for some EV owners.

The biggest issue is not the fact that the average drive can be met – the issue is with the perception that some small fraction of trips may not be possible or difficult because of insufficient charging infrastructure.

If quick chargers were as ubiquitous as gas stations, then if you get caught slightly short of you destination, no big deal. But right now if you miscalculate this can quickly turn into a big hassle. Just getting stranded once is enough to turn people off of EVs.

when it is your car, and your means of transportation, “average” figures aren’t good enough. you want reliable transportation, which means you don’t ever want to get stranded. if you live in a major metropolitan area, it is fairly easy to drive more than 100 miles in a day. when you are running errands, time is typically tight, you want your car to be able to take you where you want to go when you want to go; you typically don’t want to be forced to wait for your vehicle to recharge enough for you to continue travel. i think that the focus on pushing BEVs is not a good thing for adoption of electric vehicles among the general public. maybe EV enthusiasts like BEVs, but EV enthusiasts aren’t always practical; i mean, EV enthusiasts were big fans of the EV1, which was a completely impractical vehicle. i think that the better way to go is PHEV: PHEVs can replace gasoline for average driving, plus offer gasoline generator backup for above average driving scenarios. furthermore, PHEVs can recharge, if you have the time to recharge while traveling, but they can also refuel in the conventional manner if you don’t have… Read more »

Exept it turn out it’s EREV that are more expensive than comparable BEV.
So, the point of “pushing” too hard for BEV ain’t so clear.
I would have love to buy an EV1 but that wasn’t possible.
Was it such an impraticable car?
Frome all the review of people who actually drove it, it seems not.
They might have been just EV enthusiast, but I doubt it.

“when you are running errands”

When you’re running errands, you typically park for at least 15 minutes at a time. Imagine if you were able to conveniently QC or even just L2 charge (30A L2 is good for about 25 miles an hour), that would likely be plenty to get you plenty of range without any additional waiting.

But, that of course means that charging stations need to be ubiquitous as I mentioned above.

“no comment” said:

“what is important for adoption of PHEVs is to not make the battery unnecessarily large because that makes the vehicles more expensive and in turn makes them a less appealing option to the general market purchaser who will view ICE vehicles as an option.”

The problem here is that there is going to be wide disagreement over what “unnecessarily large” means. For example: For me, the GM Volt’s ~38 mile range would be wholly inadequate, and I would never buy a PHEV with so short an electric range.

Altho in theory a PHEV would suit my needs better than a BEV, in practice I’d rather have a Leaf than a Volt, because I’d wind up either having to burn gas fairly often, or else I’d have to stop to recharge a lot more often than I would if I drove a Leaf.

This situation results in Volt owners stopping for a recharge en route more often than Leaf owners, at least according to this study:

And sadly, there isn’t any PHEV on the market with an electric range longer than the Volt. I hope that will change soon!

In ICE cars it is often stated that “noone gets the EPA fuel economy”. That is partly because the EPA numbers are based on a standardized test that has a maximum speed, I believe, of 47 mph. For the same reason, BEV values are misleading when your typical travel uses in-town freeways where speeds are typically 70-75 mph. An in hot climates like the US southwest, where I am, battery fade is a serious issue.

i have a chevrolet volt. i would say that the epa number for electric range is fair. to my experience, the epa figure is really a kind of annualized average range; in cold climates i get more range during warmer months and less range during colder months (when i am running the heater). but the average between warmer and colder weather ranges is about what the epa states for the chevrolet volt.

EPA highway test averaged something like 47mph. The high-speed highway test has a maximum speed of 80mph, but the typical speed are still not that high.

Once 200 mile BEV cars are available with liquid cooled battery packs, I will take a serious look. (Hopefully next gen Leaf, Chevy Bolt & Model 3) Until then I’m leaning toward a PHEV 50 type solution (since I can’t afford a Tesla).

I think it is also fair to say that a one-seat, one door vehicle will meet the needs of most people on most days. I almost never have 4 or 5 people in my 5 seat, 4 door car. But I wouldn’t seriously consider a 2 seat, 2 door car, even though I expect it meets my “needs” always, and my “wants” >95% of the time.

I agree with a lot of the comments that the statistics provided do not necessarily meet real world. However, I have been driving a Nissan Leaf to work (30 miles round trip) for over 2 years in Colorado without ever dropping below 30% of my remaining battery. Our second car is an ICE and obviously meets our longer trip needs. If automakers start offering 150+ mi range EV’s (I’m talking about affordable cars for the masses, not Tesla), I’m not sure I’d be willing to pay more for the extra range if a 80 mi range version is still offered. To replace our ICE car with a long range EV would obviously be a desire, but I still think there is a place for shorter range EV’s.

Concur with the hope that the next generation of affordable EVs (~2017) will offer multiple battery pack sizes for commensurate prices. Then let each person decide what works for them.

My leaf is coming up on 2 years old.

I haven’t lost any discernible charge. And the lease is 3 years.

What is the issue exactly????

The issue is that sometimes the battery loses capacity over time. Like your cell phone or laptop does. It is particularly a problem is locations that have sustained high ambient temperatures (such as Phoenix and some other desert cities). Obviously losing a small amount of capacity after 10 years might be ok, but losing significant capacity every year is a problem. Especially since range is already a concern. Like alot of things, it depends on how it is used. Does your use require frequent deep discharges – such as on a daily basis? What is the climate where you are?., etc.

I guess I should also have added- how effective is the cars battery cooling scheme. The Volt, and some other cars use an active, liquid cooling scheme(which seems to work well). The Leaf uses a passive air-based cooling scheme (which seems to contribute to the issue).